Use of bomb-produced C-14 to evaluate the amount of CO2 emanating from two peat bogs in Finland

We used moss increment counting to obtain well-defined samples of the topmost peat layers of two Sphagnum fuscum hummocks. The two ombrotrophic bogs, Lakkasuo in central Finland and Korvinsuo in eastern Finland, are of different ages, covering 3 and 9 ka, respectively. Using AMS dating, we traced bomb-produced C-14 through the topmost parts of the two peat profiles. A well-defined C-14 activity peak was found in both sequences dating the corresponding layer to AD 1965. A comparison between the maximum peat activities and the corresponding atmospheric values for the period of interest provides an opportunity to evaluate the amount of CO2 emanating from the decaying peat bog, and taken up by the living sphagnum plants. Considerable variations in delta(13)C values were also observed. These variations indicate, at least partly, annual variations in the emission rate of CO2 from decomposition of older peat in the bog, and are connected with climatic factors such as temperature and precipitation.